Optical transmitters are widely used in communication networks. One such use is to replace the electrical cabling which transmits an analog signal that drives the transmission antenna of a mobile communication network. This is useful when the base station controller or other equipment that generates the radio frequency (RF) signals to be transmitted is located remotely from the transmission antenna.
It can be challenging to carry the analog signal over electrical cabling, due to the large weight and poor signal integrity of electrical cables. Therefore, the analog signal may be carried on an optical fiber using an optical carrier. This and similar arrangements are known as a radio-over-fiber (RoF) system or an RF-over-fiber system.
The analog signal used to drive the transmission antenna may be converted from digital signal by a DAC. For example, the digital signal may be converted to an analog signal using a digital-to-analog (D-to-A) modulator. In an optical transmitter, an optical carrier signal, typically produced by a continuous wave (CW) laser diode, is modulated to carry digital data encoded on the CW analog waveform by means of such a DAC.
However there is a demand for ever increasing speeds, and smaller footprints for such systems. Accordingly there is a need for an improved optical transmitter which can operate at high speeds. Photonic Integrated Circuits (PIC) technologies can provide high speed and small footprint.
Accordingly, there is a need for a system and method that at least partially addresses one or more limitations of the prior art.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.